Link previews
Link previews are available in some places in Nextcloud. There are 3 types of link preview:
- The ones for links that are supported by a reference provider
Without custom reference widget (uses a default generic style, image + title + description)
With custom reference widget (implemented by the app which supports the link)
Default ones from OpenGraph information. This is the fallback for every unsupported link
Where do they appear?
The link previews provided by the Nextcloud reference system appear in the following places:
- Text (and Collectives pages, Notes, Deck card comments, Files comments etc...)
Directly in the document content, next to the links
Only one link preview per paragraph is rendered
Custom widgets can be rendered
- Talk
In the messages
Only one link preview per message is rendered
Custom widgets can be rendered
- Nextcloud Office
In the document content when hovering on links
Custom widgets are not rendered
How does it work?
The Nextcloud frontend asks the server to resolve the links via an API request. A rich object is returned as a response and is used by the frontend to render the preview.
The apps can optionally register a custom reference widget to render a specific rich object type (on the links it supports). Therefore the apps have complete freedom over how some previews look like.
Known link preview providers
Collectives: Links to Collective pages
Tables: Links to tables
Deck: Links to boards, cards and comments
Talk: Links to conversations
GitHub integration: Links to GitHub issues, pull requests, comments and repositories
GitLab integration: Links to Gitlab issues, merge requests, comments and repositories
Zammad integration: Links to Zammad tickets
Reddit integration: Links to subreddits, publications and comments
Mastodon integration: Links to members and toots
The Movie Database integration: Links to people, movies and series
OpenStreetMap integration: Location links from OpenStreetMap, Google maps, Bing maps, Here maps and Duckduckgo maps
Giphy integration: Links to GIFs
Notion integration: Links to Notion documents
Peertube integration: Links to videos